Solve for $x$ and $y$ using substitution. ${x+5y = -7}$ ${x = -y+1}$
Answer: Since $x$ has already been solved for, substitute $-y+1$ for $x$ in the first equation. ${(-y+1)}{+ 5y = -7}$ Simplify and solve for $y$ $-y+1 + 5y = -7$ $4y+1 = -7$ $4y+1{-1} = -7{-1}$ $4y = -8$ $\dfrac{4y}{{4}} = \dfrac{-8}{{4}}$ ${y = -2}$ Now that you know ${y = -2}$ , plug it back into $\thinspace {x = -y+1}\thinspace$ to find $x$ ${x = -}{(-2)}{ + 1}$ $x = 2 + 1$ ${x = 3}$ You can also plug ${y = -2}$ into $\thinspace {x+5y = -7}\thinspace$ and get the same answer for $x$ : ${x + 5}{(-2)}{= -7}$ ${x = 3}$